Generally, an electronic throttle control system determines a target throttle valve position, based on an accelerator pedal position and other engine operating parameters, and electronically regulates the position of the throttle valve. In a conventional electronic throttle control system the throttle valve is fully closed by a return spring when the throttle actuator is not powered. To draw air into the engine while the throttle valve is fully closed, a bypass line and a bypass valve are provided. The bypass valve closes or opens the bypass line. If the bypass valve is opened, air is induced into the engine even while the throttle valve is fully closed. Thus, the engine may operate at a predetermined speed.
The conventional electronic throttle control system must include the bypass line and the bypass valve so that the engine can function in case of a throttle control system failure. The addition of the bypass valve and bypass line complicates the system. In addition, control of the bypass valve is needed, so the conventional electronic throttle control system becomes even more complicated. Furthermore, as the return spring wears, precise control of the position of the throttle valve becomes difficult.
The information disclosed in this Background of the Invention section is only for enhancing the understanding of the background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art that is already known to a person skilled in the art.